Harbours (5)
I believe the answer is:
ports
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">harbours</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ports that I've seen before include "Places where people and merchandise enter or leave a country" , "Harbours" .)